Monitoring and detection circuits for spun filaments



July 28, 1964 R. HORNE ETAL MONITORING AND DETECTION CIRCUITS FOR SPUNFILAMENTS BY ROBERT D.'TA v1.0

KM; ATTOR EY Filed Feb. 15 1961 United States Patent M 3,142,831MONITORING AND DETECTION CIRCUITS FOR SPUN FILAMENTS Ronald Horne andGeorge B. Price, Pensacola, and Rob! ert D. Taylor, Milton, Fla.,assignors, by mesne assignments, to Monsanto Company, a corporation ofDelaware Filed Feb. 13, 1961, Ser. No. 88,952 1 Claim. (Cl. 340259) Thisinvention relates to monitoring circuits and more particularly tocircuits for monitoring the denier of spun filaments.

In the manufacture of spun filaments it is of utmost importance that thedenier or diameter of the filaments be uniform. Variations in denierwillconsiderably lower the quality of the yarn, since these variationswill be visible in the finished fabric. One of the causes of deniervariations is fluctuations in the pressure applied to the spinningsolution in the spinning head. A drop in pressure behind the spinnerettewill result in a reduction in the diameter of the spun filaments. Thisis commonly called spinnerette starvation.

In one type of spinning operation, commonly known as melt spinning, thefilaments leave the spinnerette and pass downward through a chimney torolls which advance the filaments to a takeup device. A stream of air isdirected transversely across the chimney to cool and solidify thefilaments. The embodiment of the invention disclosed herein monitors thedenier of the filaments passing through the chimney. Thus, a deniervariation is detected at once. In conventional spinning operationssamples of the filaments are taken and measured for denier. Thedisadvantage of this method of inspection is that many yards ofundersize yarn may be produced before the defect is detected. Of course,all of this yarn will be of very poor quality and may even be unusable.

One of the objects of this invention is to provide a novel and improvedmonitoring system.

Another object of this invention is to provide a system for monitoringspun filaments to detect denier variations therein.

A further object of this invention is to provide a system forautomatically and continuously monitoring the denier of spun filamentsat the spinnerette.

Still another object of this invention is to provide a circuit whichoperates an alarm or control in response to a decrease in denier of spunfilaments.

One embodiment of the present invention contemplates a monitoring systemwherein a light beam is projected across a spinning chimney onto asensitive light-responsive resistor which is connected in a monitoringcircuit. If the proper pressure is maintained behind the spinnerette thefilaments will be of proper size and the air stream will sweep thesefilaments toward one side of the chimney to keep them out of the lightbeam. If, however, the pressure behind the spinnerette drops, thediameter of the filaments will decrease and one or more of the filamentswill move into the light beam. This causes a variation in the resistancevalue of the light-responsive resistor to trigger the monitoring circuitwhich operates an alarm or control.

Other objects and advantages of the invention will become apparent whenthe following detailed description is read in conjunction with theappended drawing, in which the single figure illustrates one embodimentof the invention and shows a schematic diagram of the monitoring circuitand a fragment of the spinning chimney.

Referring now in detail to the drawing, fragments of a spinning head 11and a spinning chimney 12 are shown. Filaments 14 are formed when amolten spinning solution is forced under pressure through the holes inthe spin- 3,142,831 Patented July 28, 1964 nerette (not shown) heldwithin the spinning head. A stream of air from a nozzle or manifold 17connected to an air source 18 is directed laterally across the spinningchimney to cool and completely solidify the filaments 14. Thesefilaments then pass between guide pins 19 and are taken up at a constantspeed by well known equipment (not shown).

If the pressure in the spinning head 11 is at the proper value thespinning solution will be forced through the spinnerette holes at a highenough speed to provide a slight amount of slack in the filaments 14.This slack will allow the airstream to deflect the filaments from astraight path, as illustrated in the drawing. If however, the spinninghead pressure drops, the solution will pass through the spinneretteholes at a slower rate. This will cause the takeup mechanism (not shown)to pull the filaments back onto a straight path and into alignment witha pair of slits 22 and 23 in the spinning chimney. Because of theconstant speed takeup and the slower rate of passage of the solutionthrough the spinnerette holes, the denier of the filaments 14 will bedecreased. Thus, a decrease in denier is accompanied by a movement ofthe filaments from the deflected path to a straight path.

A light source 26 positioned adjacent to the slit 22 directs a lightbeam laterally across the spinning chimney, through the slit 23 and ontoa sensitive cadmium-sulphide resistor 27 of a well known type whichvaries in resistance in response to variations in the intensity of thelight beam.

The cadmium-sulphide resistor 27 is connected between terminals 28 and29 in series with a 2000 ohm potentiometer 33 and a 51K resistor 34, allthree of these elements being connected in parallel with a seriesconnected ohm resistor 37 and transistor 38 connected between theterminals 28 and 29.

The base of the transistor 38 is connected to the tap of thepotentiometer 33, while the transistor emittor is connected to the 100ohm resistor 37. The collector of the transistor is connected through anormally closed, manually operated, switch 41 to the terminal 29.

A battery 42 is connected in series with a relay 43 between theterminals 28 and 29 for applying power to the circuit. The relay 43 isprovided with a contactor 46 which is closable to connect an alarm lamp47 to a battery when the relay 43 is pulled in, the relay 43 pulling inat 2.4 ma. and dropping out at 2.2 ma.

In operation of the monitoring system, the filaments normally follow thepath shown in the drawing and the intense light beam holds theresistance of the light-responsive resistor 27 to a low value. Thetransistor will not be conductive. A small amount of current will flowthrough the circuit path which includes the relay 43 the 51K resistor34, the potentiometer 33 and the light-responsive resistor 27. However,this current will not be great enough to pull in the relay 43.

In the event of a pressure drop in the spinning head, the filaments 14will assume a straight path and will partially block off the light fromthe source 26. This causes an increase in the resistance value of thevariable resistor 27 which in turn causes the transistor 38 to becomeconductive. This allows more than 2.4 ma. to flow through the relay 43,thereby pulling in this relay to close the contactor 46 to connect thebattery 48 to the alarm lamp 47. This indicates to the operator that thespun filaments are not up to the desired quality so that he can begin animmediate check of the spinning apparatus to determine what has gonewrong. If it is desired, the closing of the contactor 46 can be used tooperate a control device of some sort. For example, a device forstopping the spinning operation could be substituted for the lamp 47.

The variable or light responsive resistor 27 is so sensitive that themovement of a single 3 denier filament into the light beam will causethe transistor to become conductive.

This system provides an'imme'diate inspection of spun filaments, so thatnecessary corrections can be made at once rather than after a largeamount of off-denier yarn has been spun. Also, this system provides anautomatic inspection of all of the yarn rather than just short portionsas is the case with conventional inspection.

It is to be understood that the embodiment disclosed herein is merelyillustrative and that this embodiment may be altered or amended and thatnumerous other embodiments may be contemplated which will fall withinthe spirit and scope of the invention.

What is claimed is:

A system for detecting a decrease in denier of melt spun filaments,comprising a spinning chimney through which the filaments pass, saidchimney having a pair of slits in the opposite sides thereof, a nozzlepositioned adjacent to the chimney for directing a stream of air fromthe back of the chimney thereacross to sweep the filaments to the frontof the chimney and in a direction normal to a line extending throughsaid slits, a light source positioned adjacent to one of the slits fordirecting a beam of light along said line through said slits, a cadmiumsulphide resistor positioned adjacent to the other slit for receivingsaid light beam, said resistor having a resistance value thereofconnected to the tap of the potentiometer, a relay,

a battery connected in series with the relay between the terminals, andalarm means operated by the relay, said transistor conducting to operatethe relay in response to a decrease in the resistance value of thecadmium sulphide resistor.

References Cited in the file of this patent, UNITED STATES PATENTS2,233,483 Metcalf Mar. 4, 1941 2,273,105 Heckert Feb. 17, 1942 2,323,128Hare June 29, 1943 2,682,144 Hare June 29, 1954 2,922,188 Bossen Jan.26, 1960 2,979,628 Goon Apr. 11, 1961 2,979,766 Briggs et a1. Apr.18,1961 2,982,994 Fernstrom May 9, 1961 FOREIGN PATENTS 692,726 GermanyJune 26, 1940 917,296 Germany Aug. 30, 1954

